A wide array of consumer goods and retail products are packaged in containers or articles that are produced by thermoforming. Such thermoformed articles are typically labeled after they are formed. To produce a thermoformed article, a polymeric sheet or film is first heated to its softening point. Once the sheet or film becomes pliable, the sheet is positioned into a mold cavity by application of vacuum to a side of the sheet while the sheet is appropriately positioned relative to the mold. Alternatively, a male member can be used to urge or otherwise position the sheet into the female mold cavity. In either technique, the heated and pliable sheet is pressed or otherwise drawn to matingly contact the mold cavity. As a result, the sheet adopts a desired configuration corresponding to that of the mold cavity. After cooling, the formed article is removed from the cavity. The article is then subsequently labeled in a separate operation either by the thermoforming manufacturer or by a third party such as a convertor or end user downstream. These conventional processes are generally satisfactory. However, requiring separate labeling operations to produce a final labeled article increases production costs, complexity, and inventory.
In-mold labeling techniques are also known in which a label is incorporated into an article during thermoforming of the article. In these methods, labels are placed or otherwise positioned in the mold cavity. Upon contact with the heated article during thermoforming, the label is then affixed to the article. In-mold labeling techniques suffer from several disadvantages and may require special molding equipment, practices, and controls to accommodate placement and retention of labels within the molding cavity.
Alternatively, another technique is known in which label markings or indicia are incorporated into a sheet or film assembly prior to thermoforming. In this technique, a preprinted formable web is manufactured by first reverse printing one ply of a multilayer formable web and then adhesively laminating the reverse printed film to a second layer of the same (or different) material in an offline lamination process to produce a finished formable web that is provided to the thermoforming operation as a finished roll. This technique offers certain advantages, however does not remedy all of the disadvantages associated with conventional or other known thermoforming and labeling operations.
Therefore, a need remains for a strategy for readily producing a labeled finished thermoformed article. Specifically, a need exists for a method of thermoforming to produce a finished and labeled article, in which the method does not require any pre-lamination operations involving one or more layers. It would be particularly desirable to provide a method for producing a finished and labeled article in a single continuous process.